ethylene glycol

Bruce

and pex pipe. A friend of mine just had a radiant heat system installed by a contractor.It is a wood fired boiler and they used ethylene glycol.I know that dan's books say not to use it with pex pipe.Would you recommend that he change it out to proplyene .
thanks Bruce

hot_rod

Should be fine

IF he used a glycol designed for hydronic use. Stay away from automotive blends regardless if they are ethylene or propylene based. Ethylene is a bit better heat transfer fluid than propylene, and is actually more biodegradable than propylene, should it spill.

It does have a higher toxicity listing, and this is the concern when mixing in applications with potable water HX,s.

The glycol producers I have talked to indicate it should not be a problem with pex. (stay away from PVC, however)

Best to get the OK, via e-mail or in writing, from the manufacture of the PEX used.

hot rod

To Learn More About This Contractor, Click Here to Visit Their Ad in "Find A Contractor"

Bruce

reclaimed

Thanks hot rod. I think they used reclaimed antifreeze,might of been auto type.If so ,can they put in some additives to make it OK .thanks Bruce

Duncan_2

Open systems

Hey hot rod, this post and another one below got me thinking about open system wood boilers.

It's been mentioned that glycols and open systems don't get along, that it encourages glycolic acid, I think?

And it's a fact that two liquids with different vapor pressures, mixed together will evaporate at different rates. Like glycol and water. The water goes away and the glycol is more concentrated in this case, I think.

What are you seeing out there, regarding open system wood boilers and their antifreeze chemistry over the long haul?

hot_rod

Good point Duncan

I wasn't considering an open system with glycol. Typically the outdoor wood furnace type of wood burners just get plain water with a corrosion inhibitor. Usually no more than an oxygen scavanger in the product the wood furnace manufactures sell. Really no need for glycol if the fire, or pump is kept running on the outdoor open systems boilers.

If, for whatever reason, one were to consider glycol in an open loop system, maintaining the O2 scavangers would certainly be the challange!!

It's always the ph number you need to watch with glycols. This is the first indication that the O2 scavanger portion of the glycol is used up. Time to beef it up, or prepare to pay the glycolic acid queen dearly

I'd have to check with my glycol expert regarding seperation when used in an open system, never had a reason to try that, yet I would think with a pump running things would stay blended well.

I know for a fact when glycol is spilled on the boiler insulation, the water evaporates after a short while, and the remaining sticky, saturated "mess" is VERY VERY flamable. Seen that with my own two eyes. Be very afraid of that! Scary and ugly when a boiler catches on fire!

hot rod

hot_rod

Wouldn't be

my first choice. Automotive anti freezes are blended with silicates, which can turn into a thick silicate gel and actually reduce heat transfer.

Although, virtually every carwash snow and ice melt system I have worked on over the years has been filled with automotive antifreezes, it seems. The pile of empty jugs in the corner is the tip off.

Maybe something to do with the word car, carwash, and car antifreeze!! Although I suspect the decision to use automotive antifreezes is probablly price driven.

Hard to pass up a "blue light special" on gallon jugs of antifreezes at a fraction of the cost of brand name hydronic glycols.

hot rod